Effects of dietary xylooligosaccharides on the performance, egg quality, nutrient digestibility and plasma parameters of laying hens

This study was conducted to determine the effects of dietary supplementation with xylooligosaccharides (XOS) on the laying performance, egg quality, nutrient digestibility and plasma parameters of Lohmann hens. A total of 1080 Lohmann laying hens (28 weeks of age) were assigned to six treatment diets that included XOS at concentrations of 0, 0.1, 0.2, 0.3, 0.4 or 0.5 g/kg for 8 weeks. Each treatment had six replicates with 10 cages (3 birds/cage). Egg production, egg weight and feed intake were recorded daily. Egg quality traits were recorded every 4 weeks. Plasma parameters were evaluated, and a metabolic experiment using 36 birds from each replicate was conducted at the end of the study. The results show that XOS supplementation had no effect on the production performance but could significantly improve the quality of the eggshell; eggshell thickness and eggshell relative weight showed a linear or quadratic response to increasing dietary XOS (P < 0.05). However, XOS supplementation did not influence other egg quality characteristics, such as yolk relative weight, Haugh unit, yolk color and shell strength. On the other hand, XOS supplementation could significantly increase the apparent digestibility of the calcium (P < 0.05). Moreover, plasma glutamic-pyruvic transaminase (GPT), cholesterol, high-density lipoprotein (HDL), and very low-density lipoprotein (VLDL) decreased linearly (P < 0.05) with the increasing dietary XOS concentration. XOS can be concluded to be an effective feed additive because it improves the quality of the eggshell by increasing the apparent digestibility of calcium and because it decreases the plasma GPT, cholesterol, HDL, and VLDL of laying hens.